Fine Structure of Salt and Water Uptake in the Land-Grab,<i>Gecarcinus lateralis</i>

Abstract

The salt-absorbing tissue is found in the respiratory lamellae of the gills in the form of a highly interdigitated epithelium. The folds of the epithelium are supplied with mitochondria in the form of “mitochondrial pumps.” Intercellular spaces between the folds also satisfy the morphological requirements for Diamond's model system for water transport based on his theory of standing osmotic gradients. Most of the osmoregulatory tissue is localized in the three most posterior gills, which in turn rest on the pericardial sac. It is suggested that the pericardial sac transfers ground water to the gills for salt and water absorption. The pericardial sac serves for storage of water and as a hydraulic assist during the molt.